Such a method and such an operating device are known from DE 10 2009 051 968 A1. The appended FIGS. 1 and 2a, 2b and 2c originate from this application and serve to explain the problem on which the present invention is based. In accordance with the circuit arrangement shown in FIG. 1, a lighting system comprises a control apparatus 1 with an operating element 2, which can be in the form of a pushbutton or a rotary button. The control apparatus 1 is connected on the input side to a phase L of an AC voltage system USys., for example to the power supply system conventional in Europe with an AC rms voltage of 230 V. On the output side, the control apparatus 1 is connected to an operating device 5 via a supply line 3, wherein the operating device 5 is additionally connected on the input side to the neutral conductor N of the AC voltage system USys.. A direct connection of the control apparatus 1 to the neutral conductor N is not provided. The operating device 5 is used for operating a light-emitting means 6. The light-emitting means 6 may be a fluorescent lamp, for example. By way of example, the operating device 5 can also be integrated in a lamp, as is the case for an energy saving lamp (ESL). A converter 4 converts electrical energy from the AC voltage system USys. into a form for operating the light-emitting means 6. The converter 4 as part of the operating device 5 comprises the necessary equipment for operating said operating device. The operating device 5 and the light-emitting means 6 in the present example form an energy saving lamp, with the voltage UESL being present at the input of said energy saving lamp. The operation of other light-emitting means 6 by means of such an operating device 5 is likewise possible.
By setting the operating element 2 of the control apparatus 1 it is possible, for example by rotating a rotary knob or actuating a pushbutton, to input control information which is converted by the control apparatus 1 into modulation which is transmitted with the supply voltage transmitted by the supply line 3 to the operating device 5. The modulation is decoded on the lamp side by a decoder 11 associated with the operating device 5 and is used for actuating the light-emitting means 6 via the converter 4. For this purpose, the control apparatus 1 and the operating device 5 have corresponding signal processing units, for example microprocessors.
One or more further operating devices can be connected to the control apparatus 1, in parallel with the operating device 5. These parallel-connected operating devices are then operated via the control apparatus 1, which is connected upstream of said operating devices.
The control apparatus 1 comprises a modulator (not illustrated in the figures) for modulating control information to specific components of the half-cycles of the AC voltage system USys. which are conducted to the operating device 5. The control information itself is set via the operating element 2, as has already been explained briefly above. This control information may be, for example, brightness information and/or another operational setting of the operating device 5, in particular of the light-emitting means 6 associated with the operating device 5.
The operating device 5 comprises a shunt 9, which can be activated via a switch 10. The decoder associated with the operating device 5 for decoding the transmitted control information is characterized by the reference symbol 11. On the input side, the operating device 5 has a full-bridge rectifier 12, which is connected to the supply line 3 and the neutral conductor N. The decoder 11 applies the decoded control information to the converter 4 operating the light-emitting means 6. The decoder 11 likewise actuates the switch 10. The operating device 5 can comprise further circuits which may be necessary for operating the light-emitting means 6, for example for current limitation or for generating a relatively high frequency, which are generally implemented in an integrated converter 4 of a compact fluorescent lamp.
Furthermore, a capacitor 8 (illustrated only symbolically in terms of circuitry) is associated, as energy store, with the control apparatus 1 and is used to supply operating voltage to the control apparatus 1, as explained below. If the control apparatus 1 draws its operating current via the shunt of the operating device 5, the capacitor 8 is charged. The operating energy output of the energy store takes place in those operating states of the lighting system in which the control apparatus 1 is not drawing any energy via the shunt 9 of the operating device 5.
The positive and negative components of the AC voltage present across the phase conductor L and the neutral conductor N are rectified by the rectifier 12, with the result that two positive half-cycles are provided at the output of the rectifier 12 within an AC voltage period.
The term “modulation phase” PM used in the context of the following embodiments should be understood to mean that part of a half-cycle in which information is impressed on the AC voltage supplied to the operating device 5.
The term “supply phase” PS used in the context of these embodiments is intended to mean that part of a half-cycle in which the control apparatus 1 can be supplied with energy via a supply line between the control apparatus 1 and the operating device.
The term “shunt phase” used in the context of these embodiments is intended to mean those parts of a half-cycle in which the shunt 9 is activated by virtue of the switch 10 being switched on.
The term “operating phase” used in the context of these embodiments is intended to mean those parts of a half-cycle in which the operating device 5 draws energy for light generation.
This said, FIG. 2a shows, using the example of an energy saving lamp as light-emitting means, that the operating device draws its operating energy in an interval of between approximately 60 degrees and approximately 100 degrees of each half-cycle. The curve of the operating current consumption is illustrated by the reference symbol F, to be precise in the case of operation of the light-emitting means 6 on full power. The dashed curve F′ describes the operating current consumption in the dimmed state.
The modulation phase PM is illustrated schematically in the latter part of the half-cycle. The supply phase PS is located in the first part of the half-cycle, for example at a phase angle of between 0 degrees and less than 40 degrees. In the method illustrated, this is stepped, with a first and a second part, wherein a higher shunt current flows in the first part of the supply phase PS than in the subsequent, relatively short second part of the supply phase.
As a result of the series circuit comprising the control apparatus 1 and the operating device 5, when the shunt switch 10 is closed the control apparatus 1 can draw operating energy itself and can charge its energy store (capacitor 8). If, on the other hand, the shunt switch 10 is open, the control apparatus 1 cannot draw any power from the AC voltage applied. In order nevertheless to supply the required energy to the control apparatus 1 when the switch 10 is open, the capacitor 8 is provided, said capacitor feeding energy to the control apparatus 1 in these phases. The following half-cycles (not illustrated in FIG. 2a) likewise have the abovementioned phases since the control information to be transmitted, the so-called telegram, has generally been divided into a plurality of successive half-cycles. In addition, in the exemplary embodiment illustrated, the control information is transmitted cyclically and continuously.
FIG. 2b shows the profile of the voltage UESL at the operating device 5. During the modulation phase PM, the control information is modulated onto the AC voltage supplied to the operating device 5, to be precise with a largely constant modulation voltage. In the first part of the half-cycle, the supply phase PS can be identified, in which the control apparatus 1 acts in current-limiting fashion and therefore reduces the voltage across the operating device 5.
With reference to FIG. 2a, the first part of the supply phase is ended in time-controlled fashion. The second part ends in voltage-controlled fashion when the absolute value of the voltage between the supply connections of the operating device exceeds a predetermined voltage. In the first part of the supply phase PS, for example, currents of approximately 150 to 400 mA can flow. This current is limited by the control apparatus 1 and is used for the energy supply to said control apparatus. In the second part of the supply phase, for example, currents of approximately 20 mA flow. This current is predetermined as the maximum shunt current of the operating device 5. The first part of the supply phase PS is used for charging the energy store 8 associated with the control apparatus 1.
In order to keep the power loss in the operating device 5 and the control apparatus 1 low and to ensure a defined voltage rise at the input of the operating device 5 once the supply phase PS is complete, the supply phase is ended in the second part so as to form an intermediate level, in this case approximately 20 mA. Once the supply phase PS has ended, the operating device 5 draws the energy required for its operation in the operating phase. If this is concluded, the modulation phase PM of this half-cycle is implemented, to be precise when the shunt switch 10 is closed, wherein this shunt can in turn be at the lower level of the supply phase PS implemented prior to the operating energy consumption.
FIG. 2c shows the voltage profile during the above-described different phases of a half-cycle across the control apparatus 1. It can clearly be seen that, in the supply phase PS, there is a greater voltage drop across the control apparatus 1 than during the other phases in the latter part of the half-cycle.
In the exemplary embodiment described, the operating element 2 serves to set the brightness of the light-emitting means 6 and therefore to dim said light-emitting means. The control information to be transmitted to the converter 4 is therefore a controlled variable corresponding to a perceivable brightness value as a sensory impression. A corresponding dimming curve can be stored in the control apparatus 1 or in the operating device 5.
The modulation takes place by superimposition of a square-wave modulation voltage with a constant level on the envelope of the supply voltage applied to the operating device 5. Therefore, high-pass filtering is performed in the decoder 11 in order to isolate the data signal from the AC voltage. The voltage level of the modulation is from 4 to 15 V, for example.
In the method disclosed in the mentioned DE 10 2009 051 968 A1, a shunt is produced prior to or at the beginning of the modulation of control information. The production of a shunt serves to provide defined potential conditions in the line used for the transmission of the control information. By virtue of such a shunt, the line used for transmitting the control information is terminated with a defined impedance determined by the parasitic effects of said line. Parasitic effects such as, for example, a capacitance or inductance per unit length of line or crosstalk between lines laid next to one another can disrupt the transmission of the control information. The impedance of the shunt is now selected such that interference to be expected is effectively suppressed. By virtue of this shunt, the control information modulated onto the AC voltage supplied to the light-emitting means can be received by the lamp unit without being subject to any interference and can be decoded. Preferably, provision is made for the control information to be modulated onto the supply voltage only in those phases of a half-cycle in which the actuated light-emitting means draws no or substantially no operating energy or no notable operating energy.
Preferably, the shunt phase in the abovementioned method is also used for supplying operating energy to the control apparatus. The supply to the control apparatus takes place, as has already been mentioned, outside of the modulation phase in a supply phase, wherein the shunt is likewise activated in the supply phase of the half-cycle.
In the case of control apparatuses with the two-wire technology illustrated in FIG. 1, the control apparatus can only be supplied with energy when the operating device permits a current flow. This takes place during the supply phase. However, the AC system should also be connected to the operating device at as low a resistance as possible by the control apparatus during the operating phase as well in order that safe operation of the light-emitting means is ensured. A withdrawal of energy by the control apparatus during the operating phase should therefore be avoided or restricted to times in which the operating device only draws a low current, in comparison with a current in the environs of the system voltage maximum.
Further details are given in the mentioned DE 10 2009 051 968 A1.
By way of summary, it can be stated that the shunt is connected at least during the modulation phase PM, preferably also during the supply phase PS.
The data transmission can primarily be disrupted during operation of such an arrangement comprising the control apparatus and the operating device, for example for the purposes of dimming, on a supply system with a relatively high impedance or by other electrical appliances being connected in parallel or in series. For example, very inductive or capacitive loads which are connected to the same supply system in parallel with such an arrangement can deform the voltage applied to the arrangement.
Even the described switching-on of the shunt at the beginning of the modulation phase PM can result in a temporary dip in the input voltage UESL of the operating device 5 owing to this additional load.
Both of the abovementioned disruptive influences can result in voltage dips occurring at the input of the operating device during the modulation phase PM and being evaluated by the decoder 11 as data signal, although these have not been generated by the control apparatus itself for the purposes of data transmission.
As a result of the fact that the decoder is actively set to a defined start state at the beginning of the modulation phase, the influence of the above-described voltage dip, which is caused by the shunt being switched on, can be eliminated by virtue of the decoder actively being set to a defined state only once the shunt has been switched on. However, in this case there is still the problem that dips in the input voltage caused by external influences during the modulation phase can disrupt data transmission. This can take place both temporally prior to, during and after the actual data transmission.